Compressible rheostat



.coMPREsslaLE RHEUosTATl APPLICATION man APR. 17.11914.

1,430,007, Patentedsept. l26, 1922.

ffii

Patented Sept. 26, 1922.

UNITED STATES y '1,430,001 PATENT OFFICE.

AUGUST W. DONO?, 0F NIAGARA FALLS, YORK, ASSIGNOIQBY MESNE ASSIGN.. MENTS, TO U. S. LIGHT & HEAT CORPORATION, OF NIAGARA FALLS, NEW YORK, A

CORPORATION OF NEW YORK.

i, i COMPRESSIBLE RI-IEOSTAT.

Application filed April 17, 1914. Serial No. 832,450.

To zZZw/wmtmog/ cof/wem: 1

Be it known that I, AUGUST 7. DoNor, a citizenl of the United States, residing `at Niagara Falls, in the county of Niagara and State of New York, have invented new and useful Improvements in Compressible lilheostats,.of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.`

.This invention relates to improvements in comp'ressible rheostats. f

Compressible rheo'stats generally comprise a plurality ot contacting electrodes of carbon or other suitable material, which are adapted to vary the resistance of the circuit in which they areconnected, by variations in pressure applied to the electrodes.

ln coinpressible rheostats heretofore employed, the electrodes have been arranged in the form of a pile ot discs or' blocks of ear# bon or other material, one end of the pile being pressed'against a relatively fixed abutment, while a movable abutment at the other end vmay be moved to vary the pressure eX- erted on the pile. lith suoli a construction, the variations in pressure are not communicated ,uniformly throughout the' pile, the cohesion betweenthe discs or blocks appar-V ently causing the electrodes adjacent the' fixed abutment to be maintained in a more orlessl packed condition. The result is that the greater portion ot the'variations' in resistance is controlledfby the discs 'adjacent the movable abutment, so that the ynumber ol discs employed must be relatively great in proportion to the amount of energy dissipated inthe rheost'at. Furthermore, when the pressure has been greatly relaxed to obtain a maximum resistance, the discs at the movable end may become suiiiciently loosenedand separated to cause sparking and pitting` and sometimes rapid oxidation of the carbons. y

An object of the present invention is to provide a compressible rheostat of increased effectiveness in proportion to the amount of movement of the operating member.

Another obj ect of the invention is to provide a compressible rheostat of small size in proportion to its range.

Another object of the invention is to provide a compressible rheostat inwhich variations in pressure will Vbe transmitted sub- Sopuouy ooi'forooiy throughout tho nooos a Another object ofthe inventionis to pro` .ployed in many other'systems.

Inthe accompanying drawingst Figure l illustrates diagrainmatically, one embodiment olE the invention applied to regulate the generator in a car lighting system. y y

Figure 2 illustrates diagrammatically a modified embodiment applied to regulatethe lamp circuit of a car lighting system.

The car lighting system diagrammatieally illustrated in Figure l, includes a generator of `any preferredtype, herein illustrated ashaving an armature l and a lield winding 2. The generatorsupplies a storage battery 3 and lamps or other translating' devices 4', which are connected in parallel branches across the generator leads Sand 6` An automatic switch 7 ot any preferred type, may be arranged in one genera tor lead to connect the generator' to the load atv the proper voltage.` y,

In Figure .1"` the 'improved compressible rheostat is arrangedin series with the shunt field winding. The rheostat includes a series of discs or blocks 8of carbon or otherma-k terial, the resistance of which will depend on thevpressure applied to the series. The discs 8 are arranged in contact with each other and are conlin'ed'between theY movable abutments 9.'V The abutments 9 are'movable towards or from each other by means of a bell crank lever 10 fory each abutment, These' levers 10 are rpivoted at`1l and have theirA short arms connected as by the piv- Oted links l2, to the respective abutments 9. The longerarms of the levers are pivotally connected to a common operating member 13, which in Figure l `terms the core ofthe electro-,magnetic winding 14. In the arshunt l rangement illustrated, the winding-14 is conrent from the generator. A dash-pot 15 may be employed to steady the action of the operating parts.

In operation, the Weight of the core, Which may be aided, if desired, by a spring, tends to depress the longer arms of the bell crank levers so as to exert maximum pressure on the carbon discs. lVith the electro-magnetic Winding let connected as illustrated, in series with the generator, any increase in generator current above a predeteri'nined amount, Will tend to raise the core 13, andthereby move the abutments 9 aivay itrom each other. This will release pressure simultaneously on both ends of the pile of carbon discs, se that a very small movement of the core Will produce a relatively `great change in the resistance of the rheostat. By simultaneously reducing` pressure at both ends of the pile, a substantially uniform e''lect will be provided throughout the pile, so that the entire series of discs may be utilized, thereby greatly reducing the number necessary to piioduce a given change in resistance. high generator speeds, ivhen maximum regulating effect is demanded, the carbons Will not need to be so 'far separated as to produce sparking or burning.

Figure 2 illustrates a slightly modiiied form of rheostat. In this Ylorm the longer arms of the bell crank levers 10 are adjustably secured to the lever 16, pivoted at 17, and normally maintained by the spring 1S in position to exert a maximum pressure on the carbons. rIhe lever 16 may be moved in opposition to the spring to decrease pressure on the carbons, by means o1 a plunger of magnetic material 19, pivoted to the free end of the lever 16 and acting under the influence of the coil 20. As illustrated in this ligure, the rheostat may be arranged in series in a Work circuit and the coil 2O connected across said circuit, so that the rheostat Will tend to hold constant voltage on the lamps or other devices in the circuit.

It is obvious that either form of rheostat may be employed to regulate a generator as in Figure 1, or to regulate a load circuit as in Figure 2, and that either may be employed in many other relations, Wherever a variable pressure rheostat is suitable.

The improvements herein described are not limited to use with the specific type of compressible rheostat in connection with which they have been illustrated and described, but may be applied with equal ad- Even at very vantage to rheostats in which the resistance element is in the orm of granular material, and to many other forms of compressible rheostats.

rIhe tivo embodiments specifically described are merely for the purpose of illustrating the principles of the invention and many modilications may be made in the mechanical arrangement and operation of parts Without departing from the invention as deilned in the appended claims.

I/Vhat I claim as neuT and desire to secure by Letters Patent of the United States is:

1. In combination, a pile of freely movable contacting electrodes, a movable abutment in Contact with each end ol said pile, said abutments co-operating to hold said electrodes in place and in contact with each other, .said abutments being biased toward each other whereby said pile is normally compressed, and a common operating means for simultaneously moving said abutments away from each other to relieve said compression.

2. In combination, a plurality of freely movable contacting electrodes, movable supporting means supporting said electrodes at a plurality ot supporting points and biased to hold said electrodes normally in contact with each other under compression, and means for simultaneously moving said supporting means to relieve the compression of said elements at a plurality ol .points simultaneously.

3. In combination, a pile of contacting electrodes, a movable abutment in Contact with each end of said pile, bell crank levers adapted to move said abutments relative t0 each other, and a common operating means adapted to move said bell crank levers to simultaneously operate the same.

t. In combination, a Vpile of contacting electrodes, a movable abutment in contact with each end of said pile, a bell crank lever adapted to move each abutment, means tending to move said levers to compress said pile, and a common operating means adapted to move said levers to simultaneously release the compression at each end of said pile.

In witness whereof, I have hereunto subscribed my name in the presence of tWo Witnesses.

AUGUST WV. DONOP. Vitnesses:

TRAUT ENGEL, Gr. P. BROOKS. 

